In order to address the overwhelming demand for multi-color flow cytometry cell sorting, LIAI is requesting funds for the replacement of a Becton Dickinson (BD;BD Biosciences San Jose, CA) FACS Vantage SE that the manufacturer will no longer support, with a 9-color and 2 scatter parameter digital BD FACSAria II cell sorter. The facility already operates at near maximum capacity due to incredible demand from an institute devoted to the study of the immune system, and only by replacement of this instrument with a faster and more capable unit will the facility be able to fully support the research program. The requested instrument has been chosen because it can analyze up to 11 parameters simultaneously and will significantly enhance the ability to evaluate numerous phenotypic parameters of a cell concurrently, as well as greatly increased sample throughput/efficiency over the current instrument. Importantly, this high- speed instrument will maximize the opportunity to sort from high cell count samples and capture rare cell populations that are often technically challenging to collect. With a large group of extraordinarily high volume users, replacement of the current instrument will also leverage the ability to fully segregate conventional samples from biohazardous samples that will be run on an existing unit in a purpose built room and hood combination. This segregation will greatly increase safety and scheduling efficiencies that in total are expected to increase the facilities sorting capacity by nearly 1,000 hours per year;an urgent need in the support of over 100 NIH-supported investigators.